Dental care is critical for the health and wellbeing of your horse. Horses prehend and chew their food with their teeth, turning fibrous grasses into digestible calories and energy sources. When something goes wrong with your horse’s dentition, severe medical problems can arise.
Horses are obligate herbivores. Their diet consists entirely of plant materials, in the form of grass, hay, or grains. Most of these feedstuffs require extensive mastication to release the digestible nutrients. The equine jaw and dentition are perfectly designed for this function. The front incisors are designed to cut the grasses and the premolars and molars form a flat grinding surface.
Horses have a total of 36-44 permanent adult teeth. There are 3 incisors (front teeth) on both the upper and lower jaws. The canines are next. There can be anywhere from 1-4 present. Stallions and geldings have well developed canines. These are the fighting teeth, used to settle territorial disputes and to protect their herd. Some mares also have small vestigial canines. Behind the canines is the interdental space. This area is also referred to as the bars of the mouth. There are no teeth in this area, just mucosa (gum) covered jawbone, and it is here, where the bit sits. Next come the wolf teeth if they are present. They are the first premolars. Sometimes the wolf teeth do not erupt, even though they are present. These are referred to as “blind” wolf teeth. Then the second, third, and fourth premolars. Finally come the first, second, and third molars.
Horses, like people, have 2 sets of teeth. The deciduous, or baby teeth, arrive fairly early. They start much like human teeth, with the first incisor coming through first. This happens at about 6 days of age. Then the second incisor at about 6 weeks of age, then finally the third incisor at 6 months of age. The second, third, and fourth premolars come in at about 2 weeks of age. The permanent of adult teeth begin to push through starting with the first incisor again at the age of 2.5 years.
The permanent teeth then proceed as follows:
First incisor: 2.5 years
Second incisor: 3.5 years
Third incisor: 4.5 years
First premolar: 6 months-3years
Second premolar: 2-3 years
Third premolar: 2.5-3 years
Fourth premolar: 3-4 years
First molar: ~1 year
Second molar: 2 years
Third molar: 3-4 years
As the permanent teeth are coming in, you may see some bumps on your horse’s lower jaw. This is just a result of the tooth roots pushing up through the jawbone and causing remodeling. Once these permanent teeth erupt, though, things are not over. The horse has what are called hypsodont teeth. These are tall teeth that continuously erupt throughout your horse’s life. The teeth erupt at the rate of about 1/8 inch per year.
The upper arcade of teeth is slightly wider than the lower arcade. This helps to facilitate grinding as the horse chews in a circular motion. As your horse chews, the enamel surfaces grind across each other. Normally, there is slightly uneven (less) wear of the outside edge of upper arcade and the inside edge of the lower arcade. If there is uneven wear of the enamel elsewhere, sharp points and hooks can develop. Hooks normally occur on the upper second premolar and the last lower molar. All of these uneven edges can be sharp and cause trauma to the soft tissues of the gums, tongue, cheeks, and lips. Just imagine how painful a noseband can be is tightened over sharp edges that are sticking into your horse’s cheeks. As these tall hooks develop, they also prevent the normal circular grinding motion of the jaws. You may notice your veterinarian sticking her hand in your horse’s mouth to feel for sharp edges and moving your horse’s lower jaw from side to side. This is to determine if there are any hooks or points that are inhibiting normal motion.
It is important to have your horse’s teeth examined by a veterinarian at least once a year. For young horses, this is necessary to make sure that the baby teeth have fallen out properly. Occasionally, a baby tooth won’t fall off and will be stuck on a permanent tooth. This “cap” will need to be removed in order for the permanent tooth to come in all the way. For older horses it is important that sharp points and hooks aren’t causing pain when chewing, limiting jaw motion, or causing problems with the bit. Other more severe problems can be found early and interventions can take place sooner rather than later.
Some of the most common dental problems are discussed below.
Wolf teeth. The first premolar is much smaller than the others and is not well rooted in the jaw. This can cause discomfort for a horse with a bit in his mouth. Wolf teeth are normally removed routinely for horses that will wear a bit to prevent any problems. As mentioned earlier, sometimes these wolf teeth do not erupt, but can be under the gums and cause problems. Your veterinarian can usually feel them under the gum and remove them. Sometimes a radiograph can help to locate them.
Overbite and Underbite. An overbite, commonly called parrot mouth occurs when the upper jaw is longer than the lower jaw, placing the upper incisors in front of the lower ones. In an underbite, commonly called monkey mouth or sow mouth, it is the lower jaw that is longer, placing the lower incisors in front of the upper ones. This limits your horse’s ability to prehend food and can cause imbalance in the mouth, especially preventing the molar arcades from contacting each other to grind effectively. Regular dental care can help to keep your horse’s bite as normal as possible. In some extreme cases, surgical correction has been attempted in young horses.
Long canines. If the canine teeth grow to long, they can cut into the opposing soft tissue and cause pain. This is easily corrected by shortening the teeth.
Step mouth. A step mouth occurs when one or two teeth grow especially long due to loss of the opposing tooth. With nothing to grind against, the tooth continues to grow longer than the rest. This will prevent normal chewing. Frequent dental attention to that tooth will keep it short and in line with the other teeth. Sometimes a very long tooth may require power tools or molar cutters to get it short.
Wave mouth. A wave mouth occurs when the teeth have worn unevenly and have an undulating surface, looking much like waves when viewed from the side. This, too, will prevent normal chewing. The goal is to flatten the grinding surface so that normal mastication can take place.
Other conditions that may occur include fractured teeth and tooth root abscesses. A thorough examination and radiographs can help to diagnose these problems and direct appropriate treatment.
One condition that is not specifically tooth related, but is jaw related, is damage and fractures of the bars of the lower jaw. Some horses will incur damage to the bars of the mouth from the bit. Some horses can become painful on the bars from a particular bit. The gums and underlying bone can become inflamed and painful. Riding in a bitless bridle for a period of time until the area is no longer painful to palpation is the treatment. Fractures can also occur due to trauma and radiographs should be taken to investigate any pain or swelling in the area.
It is recommended that you have your horse’s teeth examined yearly by your veterinarian. Not every horse will need to be “floated”, that is have the sharp points and hooks filed down, every year, but it is important to check. Older horses and horses with known dental issues may require more frequent care.
Some signs that your horse may have dental issues include:
Dropping food when eating
Turning his head to chew
Undigested food or long strands of hay in his manure
Resists bit, carries head to one side
Grabs bit/chews bit
Bad breath/foul smell in mouth
Have your veterinarian do a complete physical exam in addition to examining your horse’s teeth if any of these signs occur.
By taking care of your horse’s teeth, you will end up with a horse that can maintain his weight, be free from dental pain, and be comfortable in his bridle. Don’t let cost make you put off dental care. It has been said that most horses will use their grain more efficiently when their teeth are well maintained, enough so that the reduction in feed costs more than pays for the annual dental exam.
Keep those teeth healthy and watch your horse smile! When he does, it will make you smile too.
Registered 2014 Equestrian Collections; Author: Sallie S. Hyman, VMD, DACVIM, CVA
Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian for their horses’ medical care.